Telephone system



Dec. 3, 1929. J. w. GOQDERHAM 1,738,294

TELEPHONE SYSTEM Filed Jan. 1'7, 1.928

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//VVEN TOR J0/1/v W GUUDERHAM Patented Dec. 3, 1929 JOHN W. GOODEBI-IAM, OF LABCHMUITT, NEW YORK, ASSIGNOR TO BELL TELEI HONE LABORATORIES, TNCURPGRATEB, OF NEW 'YGlEtlEI, N. Y., A CORPORATION OF NEW YORK TELEPHONE SYSTEM Application filed January 17, 1328. Serial No. 247,310.

current, which is periodically reversed by a timing device, is connected at the central office to the subscribers line during the conversational period to cause successive actuations of the meter. In these systems provision is made whereby the current source may be connected to the subscribers line only when the reversing device is in a given con dition; This precaution is taken to guard against the false operation of the subscribers meter.

According to the the present invention an advantage over these prior systems is secured.

by providing a meter operating and con trolling mechanism which may be connected to the subscribers line at any time irrespective of the condition of the source of current supply. Provision is made, however, to prevent said source from being disconnected from and then reconnected to the subscribers line while the direction of current is reversed. In this manner it is impossible for the called party to cause false operations oi? the calling subscribers meter by repeatedly opening and closing the talking circuit.

A feature of the invention is a system in which the source of meter-operating current is connected to the calling subscribers line, under control of the called subscriber, by means of a time-delay device which is inclependent of the timing device that causes the periodic reversals of said current to actuate the calling subscribers meter. The timedelay device operates at a much taster rate than the current-reversing device and will immediately reconnect the current-supply source to the calling line should it be discon nected by an opening of the called line. By this arrangement, a called subscriber cannot prevent the operation of the calling subscribers meter by opening the line momentarily at a definitepoint in the cycle of operation of the current-reversing mechanism.

The drawing illustrates a portion of a telephone system in which the subscribers lines appear at an operators position. Two of these lines, A and B, are shown terminating in jacks 3 and 5 respectively, at the operators position. The lines A and B are equipped respectively, with substation meters 1 and 2. These meters are arranged to operate at successive intervalsduring conversation in response to repeated reversals of current in the line. The central ofiice circuits are so arranged that only the meter of the calling subscribers line is actuated.

The operators position is equipped with a number of cord circuits, such as the cord C, partly shown in detail in the drawin A current reversal circuit 14 is provided in com mon to a number of cord circuits C. It is an ranged to be associated with any particular cord circuit taken in use to supply current to the calling subscribers line and to automatically reverse the direction of current flow in the line at successive intervals during the conversational period. Thesupply circuit 14: includes a source of current, a reversing relay 18, an interrupter 19, impedence coils 16 and 17 and a condenser 15.

The cord circuit C is prov ded with an individual relay 11 which serves to connect the supply circuit 14 through the left windings of the repeating coil 7 to the tip and ring conductors of the calling subscribers line. Similar relaysare provided for other cord circuits.

A detailed description will now be given of the manner in which the system operates. Assume that the subscriber of line A wishes to hold conversation with the subscriber of line B. The calling subscriber initiates the call in the usual manner and the operator responds by inserting the plug 4 of the cord circuit in the jack 3. When the plug is inserted in the jack, a circuit is completed from battery through the lamp 20, resistance 21, sleeve of the plug and jack to ground. At the same time another circuit is completed from bat tery, through the inner lower back contact of thisqci-rcuit andccunpletes-a circuit from batwteryg; through the;interrupter 23, resistance 22,

normal contact of relay 24, contact of relay 8 and thence to ground at the sleeve of the 1 jack. Each time'the interrupter closes, the

circuit just traced is completedfzto battery and shunts the lamp 20. Therefore, the lamp 2O flashes under'the control of the interrupter Next the operator manipulates her talking key'10 toconnecthertelephone set to the cord fcircuit and converses with thecalling subwriter; The depression of'thetalking key 10 completes an'obvious circuittlirougl'r theright "winding ofrelay' Relay 24 operates and flocks in' a circuit "from battery through its "le ft'winding and? front contact, contact of relay- 8-,t'o ground on the sleeve of the jack 3.

'Re'la-y' 24 at its norrnal contact opens the cir- 'cufit of interrupter 23' todiscontinue the flashing of thed'amp 20. The lamp is now 'completelyv shunted by the circuit traced through the lcft winding of relay'24 and,

a inaei acks; Following, this 8116 applies ringing'eurrent to the, alled line i'n'tlie well- .knownmannen; -When the called subscriber therefore, rem ains extinguished.

7 The operatomhaving, obtained the number vofthecall'edli'ne, seizes the plug. 6' and inserts iaiiswers,.a.circuit iscompleted from battery through the lower right winding ofthe repeating coil.Z,;supeI-'.visory relay 9, ringof the .plugfiand jack 5., thence over the loop of the jcalledline'B andreturning through the tip contacts or thejaek andiplugthrough the upper right winding of repeating coil 7 to ground. The supervisory relay 9 operates and closes a circuit from batterythrough its contact, upper back contact.v of relay 26', resistancesi27' and"28to groundthrough the sleeverofsjtheplug and jack. This. circuit is imsliuntofthe-circui't from battery through .29-and resistance28 and consequently'the l'ampis prevented from lighting.v As

.soonyafter the operation otz'relay 9, as the interrupter 25 closes its upper contact, a ciracu-it completed from battery through the contactotrelay 9, upper contacts of. said in- 'ternupter,..windingiot relayQfi, resistance 28 toigrounde Belay 26-.operates. and locks in a circu-itthrough itsinner upper contactindependentlyat the iiniterr-"upter 25.: As :soon,

tel-lowing this, as the interrupter closes its lower contacts, aIJci-rcuit is completed from ground: through. .thealower contacts of relay 26; lower contacts of l the-interrupter, lower current.

winding of relay 11, to battery. Relay 11 operates and locks in a circuit from battery through its lower winding and lower front contact to ground at the lower contact of relay 26.

The relay 11 in operating connects the battery supply circuit 14 to the calling line. The lamps 12 and 13, which have tungsten filaments, are provided to prevent sudden change in the current in the subscribers line while the contacts of the relay 11- are movingfrom one position to the other. When the inner back contacts of the relay 11 are broken. the subscribers line, instead of being opened completely, is now included in series with the lamps 12 and 13. The current flowing in these lamps heats their filaments, which have the characteristic of increasing their resistance as they become heated, thus producing a gradual decrease in the flow of An instant later the front contacts of the relay 11 are closed, and, assumingthe relay 18- to be in the position shown, current from the source in the supply circuit 14 is applied: to the subscribers line in the same direction. By preventing sudden changes of current inthe line whilethe supply circuit -is'connected thereto, objectionable noises are tlillllIliLtGCl.

contacts of relay 18 to the opposite pole of thebattery. Conversation now takes place.

At the end of measured intervals during the conversation, the interrupter 19 causes the relay 18 to energize and release. For example, relay 18 may operate and remain operated for a fifteen-second period and then.

release and remain released for another fifteen-second period, this cycle being repeated. When the relay 18 operates it reverses the direction of current flowing from the source over the calling subscribers line, thereby causing the operation of the polarized message meter 1. The chokecoils 16 and 17 and the condenser 15 serve to prevent sudden changes of current in the line due to the reversal of direction.

At the end of the conversation the subscribers replace their receivers on the switchhooks. lVhen the called subscriber hangs up his receiver, relay 9' releases and in turn causes the release of relay 26. Relay 26 releases the relay 11, provided its upper wind ing is open, which in turn disconnects the reversing circuit 14 from the calling subscribers line to prevent further operation of the meter 1.

' tacts of the plug and jack.

If the calling subscriber first hangs up his receiver his line is opened at the switchhook contacts to render the meter operating circuit ineffective. The calling subscriber by hang ing up his receiver also opens the circuit of supervisory relay 8 which in turn opens the holding circuit of relay 2 1. Relav 24 releases and the shunt is removed rom the lamp 20. The lamp 20, therefore, lights and remains illuminated until the operator removes the plug 1 from the jack 3.

It will be noted that the circuit of the calling line is momentarily opened at the con tacts of relay 18 on reversal of current. These interruptions although brief may result in corresponding releases of supervisory relay 8. Relay 8, upon releasing, opens the holding circuit of relay 24f, but this latter relay being slow to release does not retract its armature during such brief interruptions.

It will be recalled that the relay 11 when energized and locked is under control of the relay 26 which in turn is under the control of the supervisory relay 9 and the sleeve con- Should the called subscriber actuate his switchhook a number of times in succession, the relay 9 releases on each opening of the 'called line and releases the relay 26. Relay 26 in turn opens the holding circuit of relay 11. Under certain conditions if relay 11 is permitted to release the current in the calling line will be reversed thereby causing a false actuation of the subscribers meter 1. For example, assume that the relay 18 is operated so that current in the subscribers line is flowing in the direction opposite from what it flows when the relay 11 is in its normal position. If at this time the relay 11 is permitted to release due to the called subscriber flashing his switch hook, the calling subscribers meter 1 will be operated falsely. To prevent such an improper operation of the meter 1, a holding circuit is provided for the relay 11 and may be traced from ground through the contact of relay 24, upper winding of relay 11, upper front contact of said relay through the coil 16, upper front contact of relay 18 to battery. Thus, if the lower winding of relay 11 is deenergized at a time when current in the calling line is reversed the relay is held in a circuit through its upper winding.

The interrupter 19, which causes the re lay 18 to operate and release periodically, is

driven at a comparatively slow rate. For ex ample, it may be arranged to successively close and open the circuit of relay 18 at intervals of 15 seconds. The interrupter 25, however, which introduces the time-delay before the operation of relay 11, is driven at a much faster rate. Since these interrupters are independent of each other, the called party cannot defeat the charge for the ensuing 15-second interval by opening his line momentarily to release relay 11 just prior to the reversal of current by relay 18. If he attempts to do so, the fast interrupter 25 will cause the reoperation of relay 11 to reconnect the source to the calling line after a short interval following the reelosure of the called line.

Although the invention is illustrated in connection with amanual telephone system it should be understood that it may be applied to systems employing automatic switches. Furthermore, numerous changes and alterations may be made in the circuits and equipment illustrated without departing from the spirit of the invention.

While the substation instrument has been shown in a diagrammatic manner, it will be understood that any suitable type of meter may be used. For example, a register of the general type shown in the patent to Thomson No. 1,121,953, dated December 22, 191 1, is suitable.

What is claimed is:

1. In a telephone system, a telephone line and a current opera ted device therefor, a source of current, means for connecting said source to and disconnecting it from said line, a mechanism for repeatedly changing the flow of current from said source to cause the operation of said device, and means for preventing the disconnection of said source from the line when said changing mechanism is in a given condition. V

2. In a telephone system, a subscribers line and a service meter therefor, a source of current for supplying said line, means for con necting said source to and disconnecting it from the line, means for periodically changing the flow of current from said source to cause actuations of said meter, and means to prevent the source from being disconnected from the subscribefis line when said current changing means is in a given condition.

3. In combination, a subscribers line, a

service meter at the substation, a source of.

current for supplying said line, means for connecting said source to the line and for disconnecting it therefrom, means for repeatedly reversing the direction of the current flowing from said source to cause successive operations of the meter, and means for rendering said connecting means ineffective to disconnect the source from the line while the current flow is reversed.

4;. In combination, a calling line and a meter therefor, a called line, means for interconnecting said lines, a source for supplying current to the calling line, means controlled by the called party for connecting said source to and disconnecting it from the calling line, means for repeatediy reversing the flow of current from said source to cause the operation of said meter, and means for preventing the disconnection of said source from the calling line while the current is reversed.

5. 1n telephone system, a calling line and a called;line;ametenforthecalling line, means for establishing; a talking connection between; said lines, a source of current, a relay for connecting said source to and disconnecting it from the calling line, means for periodically reversing the direction of current from said source tocause the 01361 31 tion of said meter, means controlled by the called party for operatingand releasing said relay, and, means independent of the called line for preventing the release of said relay while currentis reversed.

' 6L In a telephone system, a calling subscribers line and a meter therefor, a called line means forinterconnecting said' lines, a source of current, means controlled by the called partyzt'or connecting said source to and ,disconnec ing it from the calling line, means for causing a delay between the response of the called party and the connection of said source to the calling line, means for repeatedly reversing the current from said source to cause successive operations of said meter, and means for preventing the disconnection of the source from the calling line while current is reversed.

'7. In a telephone system, a telephone line and a meter therefor, a source of current, a

supply circuit connected to said source, a relay arranged While in its deenergized con- 1 dition to connect said source to the line, said relay serving while energized to connect said supplylcircuit to the line, means for repeatedly reversing the direction of current in the supply circuit to cause actuations of said meter, and means for preventing the release ofsaid relay when the current in the supply circuit is reversed.

. 8. In a telephone system, a calling line and a meter therefor, a called line, means for interconnecting said lines, a source for supplying current to the calling line, means con trolled by the called party in answering for connecting said source to the calling line,

means for repeatedly changing the flow of current from said sourcevto cause the operation of said meter, and means independent-of said current changing means for introducing a delay between the time the called party answer-st le call and the time when said source is connected to said calling line.

9. In a telephone system, a calling line and a meter therefor, a called line, means for interconnecting said lines, a source for supply- .in current to the calling line, means con ti'Olled by the called party in answering the call for connecting said source to the calling 1 line, a mechanism including a constantlydriven interrupter for repeatedly reversing the direction of current from said source to operate said meter, and a second constantlydriven interrupter, the operation of which is independent of the operation of said first -interrupter, for introducing a delay between the time the called party answers the call and the timewhen said source of current is connected to the calling line.

10. In a telephone system, a calling line Y and a meter therefor, a called line, means for .driven at a faster rate for operating said connecting means after a short interval following the closure of the called line.

In witness whereof, I hereunto subscribe my name this 13th day of January, 1928.

JOHN W. GOODERI-IAM.

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